1. Field of the Invention
This invention relates, generally, to water filtration at the point-of-use for the reduction of undesirable contaminants and increase in the quality of taste and odor. More particularly, it relates to portable water filtration using a self-cleaning water filtration system with threaded piston that allows the system or its user to easily generate water pressure capable of achieving high quality water filtration while simultaneously cleaning the filter material.
2. Description of the Prior Art
Municipal water is treated with chlorine or chloramine in order to kill bacteria and viruses. To address consumer concern over taste and odor, as well as potential health effects caused by the excessive consumption of chlorine, stationary point-of-use water filtration systems designed to reduce chlorine, using granular activated carbon (GAC) and often certified against NSF/ANSI Standard 42, are well-known and have been effective in the art. Examples include tap water filters attached to the end of a water faucet, said filters filtering water on-demand; water filters that are installed in the water source line, said filters filtering all or part of the water flowing through the line; and refrigerator water filters that provide water filtration prior to the production of ice or delivery of water on-demand.
Municipal water treatment is an imperfect science. The levels of chlorine and chloramine may be inconsistent and are not always fully effective against microbial cysts, such as giardia and cryptosporidium. Even with treatment, some water supplies contain unsafe levels of lead from aging plumbing fixtures, as well as mercury and Volatile Organic Compounds (VOCs) introduced into the water supply through ground water leaching of industrial pollutants or agricultural chemicals. To address these concerns, manufacturers of household water filtration systems began to develop solid carbon block based filters with micro pores small enough to eliminate substantially all microbial cysts. Additionally different additives can be combined with the carbon block formula to allow for adsorption of undesirable contaminants such as lead, mercury and VOCs. These stationary systems connected to household plumbing benefit from the water pressure delivered by the municipal water systems, thereby producing the force required to push the water through the solid carbon block, achieving a reduction level of contaminants compliant with NSF/ANSI Standard 53.
Portable water filtration systems for use when hiking or camping are also known and typically use a carbon, ceramic or combination filter with a hand pump or lever manually driven by the user to draw water from a source and/or create pressure through the filtration system, expelling filtered water from the filter media. These systems are designed to reduce bacteria, protozoa and viruses that are commonly found in untreated water sources. However, these systems suffer from slow flow of water, require a high degree of maintenance with regular cleaning of their ceramic filter, and demand a large work effort on the part of the user in relation to the amount of filtered water produced.
Another type of portable water filtration system is a specially designed straw that incorporates one or more water filtration media, such as a hollow fiber membrane (“HFM”). Originally designed for third world countries where water quality is very low in order to facilitate reduction of bacteria and viruses, these filter straws are seeing more popularity as an alternative to cumbersome hiking and camping water filtration systems. However, filter straws are not conducive to filtering water for cooking, not usable for filtering water to be stored for later use (e.g., for use while away from a river, lake, or other water source), and are not designed for shared use due to cross-contamination concerns. Additionally, these straws do not address taste or odor, as HFM does not necessarily absorb particulates but simply stops the flow of particulates larger than its pore size.
Another filtering methodology known in the art is the incorporation of a portable water filter into plastic squeeze bottles. Because plastic squeeze bottles can generate only minimal pressure, granular activated carbon is the primary filtration media used since these devices produce insufficient and/or unregulated pressure to drive water through a ceramic filter or solid carbon block, which are substantially denser. Thus, the highest rating this type of water filter bottle can receive is NSF/ANSI Standard 42. This degree of water filtration is not sufficient to address consumer concerns regarding other contaminants in their water that are embodied in NSF/ANSI Standard 53—such contaminants include lead, mercury, industrial pollutants, and agricultural chemicals.
The prior art described herein only partially addresses a traveler's portable water filtration needs, forcing one to choose between a system designed for municipal water where chlorine, lead, industrial pollutants and agricultural chemicals are of primary concern under NSF/ANSI Standard 53 and a system designed for untreated (i.e., non-potable) water where the potential for bacteria, protozoa and viruses are of significant, if not primary, concern.
The prior art has not shown the application of a portable filtration device designed specifically to meet NSF/ANSI P231 Protocol. “Microbiological Water Purifiers Overview: Protocol P231”, which is incorporated by reference herein, addresses systems that use chemical, mechanical, and/or physical technologies to filter and treat waters of unknown microbiological quality, but that are presumed to be potable. Filtration to this Protocol would meet the needs of travelers visiting countries where the municipal water supply is deemed to be “Potable” but may not meet or equal the quality to which they are accustomed or acclimated. To date, conventional compact, portable water filtration devices have been unable to meet the standards for this certification. The only systems that remain close to the standards are chlorinators that simply add chlorine to the water.
Prior art has attempted to address the apparent conundrum with little success. U.S. Pat. No. 978,265 granted December 1910, to Barnett describes a hand pump that pressurizes liquid through an outlet pipe via use of a hand-rotated, threadably-engaged piston applying a force onto the liquid. While useful for a method of providing pressure Barnett fails to address the use of the pressure for filtration purposes.
U.S. Pat. No. 4,397,177 granted August 1983, to Cain herein incorporated by reference, addresses a hydraulic filter press apparatus for filtering samples of drilling mud. Cain uses a piston threadably engaged to a pump body. As the piston rotates, engaging the threads therearound, the fluid within the pump body is pressurized into the lower portion or the apparatus. The lower portion of the apparatus contains a fine metal screen, a disc filter paper, and a liquid outlet. While Cain is a filter of sorts, it lacks in portability and functionality for use in water filtration. The primary focus of Cain is in Obtaining mud samples free of water as opposed to water free of harmful contaminants.
Along the lines of Cain, several pressure filter patents exist that concern filtration of substances, but lack the necessities of drinkable water purification and portability. U.S. Pat. No. 63,090 to Phillips describes an improved press strainer, or fruit strainer, that uses a threaded screw that, when rotated and threaded into a cylinder, pressurizes and filters food items, such as fruit or butter. The cylinder is threaded along its lower portion as well to fit an output funnel. U.S. Pat. No. 7,014,817 to Hand, et al. describes a remote zero headspace extractor that places a sampling container within a stainless steel vessel. A manual piston is disposed within the vessel and underneath the sampling container. As the piston is threaded, pressure is exerted on the sampling container, which pushes the extract within the sampling container through a filter and into a bag or bottle. PCT Patent App. Pub. No. WO 1992013700A1 to Tsutsuini describes a hot runner mold apparatus that utilizes a screw plunger to pressurize and force a plasticized melt into a filter that removes any impurities in the metered melt. All of these patents lack the purpose, direction and capability of producing highly filtered drinking water.
Filters that use pressure to filter water lack the tools to be truly compact, simplistic in application and receive ratings of NSF/ANSI Standard 53. Chinese Patent App. No. CN201008766Y to Song describes an apparatus for treating water via a portable vacuum filter that is actuated by rotating a threadably-engaged piston. Japanese Patent App. No. JP11051832A to Yutaka, et al. describes an apparatus that uses a rotatable shaft coupled to a piston to apply pressure to a sample of soil, the water within which is siphoned through a filter into a container. U.S. Patent App. Pub. No. 2006/0273000 to Chung describes a “portable” water filtering device that uses a threaded piston to apply pressure onto water, forcing the water across a series of tubing and into a filtering tube. Sufficient pressure must be provided to force the water up the filtering tube and into the dispensing pipe. PCT Patent App. Pub. No. WO 2000057985A1 to Brebner, et al. describes a water filtration device including a filter member that is pressed into container via threaded piston rod. Initially, water is filled within container underneath filter member. Then the filter member is driven down through the volume of water, urging the water up through filter medium. The structure is a mesh screen that protects the water from airborne contaminants.
These various embodiments of pressurized filters span a period of over one-hundred years. They span from mining to organic, from water removal to water filtration. Yet throughout this evolution there lacks a compact, portable, easy to use, pressurized filtration device that achieves optimum filtration, via filters capable of achieving ratings of NSF/ANSI Standard 42, NSF/ANSI Standard 53, and NSF/ANSI Protocol P231.
Even with current technology that uses thread-forced pistons to push water through the filter, such as U.S. Pat. No. 8,323,490 to the current inventor, which is incorporated herein by reference, the art still deals with certain issues of cleaning the filter medium so that the filter medium can be used for a longer period of time. For example, the prior art, such as Chinese Patent App. Nos. CN 1548209 A to Jiaguo and CN 201823375 U to Chen et al, discusses fixed cleaning brushes with the filtration systems that extend the length of the filter. Also, U.S. Pat. No. 3,286,843 Kraissl describes a filter having two fixed wire brushes extending the longitudinal length of the reservoir with the filter positioned between the brushes. The filter is cleaned by manually rotating the filter allowing the brushes to clean the surface of the filter. With a different configuration, Chinese Patent App. No. CN 101539210 A to Liang discusses self-cleaning filter water faucet that sequentially includes an upper transfer channel, a filter disk, and a lower transfer channel. The filter disk includes a filter mesh, and the upper and lower transfer channels include fixed scraping strips/brushes for scraping the top and bottom of the filter disk through the filter mesh. Further, PCT Application No. WO 93/10879 to Arthur discusses a filter assembly that includes filter elements contained within an apertured sleeve, where the sleeve supports two fixed cleaning brushes for scrubbing or cleaning the outside of the filter elements.
Additionally, certain apparatuses of the prior art discuss cleaning the interior of the filter, rather than the exterior. Examples include U.S. Pat. No. 5,569,383 to Kaiser et al., U.S. Pat. Nos. 5,198,111 and 5,527,462 to Davis, Chinese Patent No. CN 202762177 U to Lei, Chinese Patent Nos. CN 202876488 and CN 202876484 U to Wei et al, Chinese Patent No. CN 203060935 U to Huanfang et al., and Chinese Patent No. CN 203154931 U Many of these references describe a filter having a cleaning unit that is axially moveable with respect to the filter within the filter. The apparatuses include a filter cleaner to clean the interior of the filter surface; in other words, the filter cleaner is the male component, and the filter itself is the female component.
Accordingly, what is needed is a self-cleaning portable water filter that can generate sufficient pressure to produce the desired or required quality of filtration. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the art could be advanced.
All referenced publications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular (problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.